The present invention is drawn to systems and methods for reducing air fade of printed ink-jet inks, particularly with respect to dye based ink-jet inks printed on porous media.
Computer printing technology has evolved to a point where very high resolution images can be prepared on various types of media. This has been, in part, why ink-jet printing has become a popular way of recording images on various media, particularly paper. Other reasons include low noise, capability of high speed recording, and multi-color recording. Additionally, these advantages can be obtained at a relatively low price to consumers. Though there has been great improvement in ink-jet printing, accompanying this improvement are increased demands on ink-jet printing, e.g., higher speed, higher resolution, full color image formation, image permanence, etc.
There are several characteristics to consider when evaluating a printer ink in conjunction with a printing surface or substrate. Such characteristics include edge acuity and optical density of the image on the surface, dry time of the ink on the substrate, adhesion to the substrate, lack of deviation of ink droplets, presence of all dots, resistance of the ink after drying to water and other solvents, long-term storage stability, and long-term reliability without corrosion or nozzle clogging. In addition to these characteristics, when printing on inorganic porous media substrates, light fade and air fade resistance is also an issue for consideration. Though the above list of characteristics provides a worthy goal to achieve, there are difficulties associated with satisfying all of the above characteristics. Often, the inclusion of an ink component meant to satisfy one of the above characteristics can prevent another characteristic from being met. Thus, most commercial inks for use in ink-jet printers represent a compromise in an attempt to achieve at least an adequate response in meeting all of the above listed requirements.
Papers used for ink-jet printing have typically included high-quality or wood-free papers designed to have a high ink absorptivity. These papers are functionally good for ink-jet printing because the ink-jet inks may be absorbed readily and dry quickly. However, such papers often do not allow for a crisp or sharp image.
In order to attain enhanced print quality and image quality as in a photograph, special media has been developed to work with aqueous inks. For example, various coated papers (art paper, coat paper, cast-coat paper, etc.) have been prepared by coating a layer comprising a hydrophilic binder and an inorganic pigment on a paper substrate. Additionally, recording sheets have been prepared by coating an ink absorptive layer on paper or other supports, e.g., transparent or opaque plastic film supports. An example of such specialty media utilizes a swelling-type ink absorptive layer, e.g., gelatin. Though swellable media provides a relatively good substrate with respect to certain image quality properties, a drawback includes the fact that swellable media requires more dry-time than other types of media. Therefore, experimentation in the area of ink-jet printing on inorganic porous media substrates has become more and more common, though such media presents its own set of challenges.
It has been recognized that it would be advantageous to develop methods and systems for reducing air fade with respect to dye-based ink-jet inks printed on inorganic porous media substrates. It has further been recognized that such methods and systems would be particularly advantageous if air fade could be reduced without the need for an additional coating step.
In accordance with these recognized advantages, the invention provides a method of printing an image on porous media with increased air fade resistance.
The ink-jet ink comprises a dye and an effective amount of water-soluble or water dispersible copolymer. The porous media substrate has an inorganic porous media coating that defines voids for accepting the ink-jet ink, thereby providing an image having increased air fade resistance due to the presence of a film formed by the copolymer of the ink-jet ink.
In accordance with a more detailed aspect of the present invention, the method includes the step of ink-jetting the ink-jet ink onto the porous media substrate, said ink-jet ink comprising a dye and an effective amount of water-soluble or water dispersible copolymer, said porous media substrate having an inorganic porous media coating that defines voids for accepting the ink-jet ink, thereby providing an image having increased air fade resistance due to the presence of a film formed by the copolymer of the ink-jet ink.
The ink-jet ink preferably comprises a dye and a water-soluble or water dispersable copolymer in a vehicle carrier. The porous media substrate provided can include an inorganic porous media coating, such as a silica- or alumina-based coating. Such a coating can provide voids to be filled by the ink-jet ink. Once the appropriate ink-jet ink and the porous media substrate are provided, the step of ink-jetting the ink-jet ink onto the porous media substrate can be carried out, providing an image having increased air fade resistance. In an alternative embodiment, a system for printing an image on porous media with increased air fade resistance can comprise an ink-jet ink, a porous media substrate, and an ink-jet pen containing the ink-jet ink and configured for printing on the porous media substrate. The ink-jet ink can comprise a dye and a water-soluble or water dispersable copolymer in a vehicle carrier. The porous media substrate can have an inorganic porous media coating. Such coatings can provide fillable voids for the ink-jet ink to enter. An ink-jet pen can also be present that is configured for ink-jetting the ink-jet ink onto the porous media substrate. With this arrangement, upon ink-jetting the ink-jet ink onto the porous media substrate, the ink-jet ink can fill the voids and the copolymer portion of the ink-jet ink can substantially seal dye molecules of the ink-jet ink within the voids.
Additional features and advantages of the invention will be apparent from the detailed description which follows, taken in conjunction with the accompanying embodiments and examples.